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Susac syndrome (SS) is the triad of encephalopathy, branch retinal artery occlusions (BRAOs), and hearing loss. Migraines may herald and accompany encephalopathy. Little is known about pathogenesis. Based on light microscopic findings in brain biopsy material analogous to anti-endothelial cell antibody (AECA)-mediated microvascular injury, we postulated that SS microangiopathy was attributable to AECAs. We examined serum samples from 11 patients with SS for AECAs; 9 were positive by indirect immunofluorescence and Western blot studies. A highly distinctive band on Western blots corresponding to a 50-kDa protein was observed in 8 positive SS samples; the other positive case exhibited specific reactivity with a protein band at 40 kDa. Of the 2 negative cases, 1 had been inactive since 1988; the other was an abortive variant characterized solely by BRAOs. There was enhanced surface binding of SS serum using live endothelial cell substrates compared with samples from healthy subjects. Additional serum samples from apparently healthy patients, 2 with atypical migraines, and patients with other forms of autoinflammatory disease did not show the distinctive band of immunoreactivity. SS is a distinct autoimmune endotheliopathy syndrome associated with AECAs; the antibody target seems specific in many cases and may be a disease biomarker. The exact role of AECAs in disease propagation remains unanswered.

Purpose This article describes the first retinal histopathologic findings in a patient with Susac's syndrome (SS). Design Observational case report. Participant A 51-year-old white woman diagnosed with SS. Methods Eyes from a 51-year-old white woman diagnosed with SS were obtained at autopsy. One retina was dissected and processed for adenosine diphosphatase (ADPase) flat embedding. Selected areas were processed further for transmission electron microscopy. Main Outcome Measures Histopathologic examination using ADPase flat-embedding technique. Results There were vaso-occlusive changes in the retinal periphery resulting in small areas of capillary dropout. Cross-sections demonstrated serous filled spaces between the retinal blood vessels and the internal limiting membrane. Lumens adjacent to these spaces appeared compressed and sometimes closed, but without thrombosis. Decreased ADPase activity in some peripheral blood vessels suggested endothelial cell dysfunction and vaso-occlusion. In the optic nerve head, numerous corpora amylacea were observed in the vicinity of capillaries with thickened walls and narrow lumens. Transmission electron microscopy demonstrated thickened and amorphous vascular basal lamina and open endothelial cell junctions in some retinal blood vessels. Conclusions The serous deposits with compression of retinal vessel lumens observed histologically probably represent the so-called string of pearls described clinically in SS. Chronic extension of these serous deposits along the vessel wall possibly are the cause of retinal arterial wall plaques as described by Gass and other investigators. In the optic nerve head, corpora amylacea are probably a result of microinfarcts resulting from optic nerve head capillary angiopathy. Accumulation of amorphous material in the basal lamina, loss of viable endothelial cells, and capillary dropout suggest that SS may be an endotheliopathy. Financial Disclosure(s) The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Background We investigated a new minimally invasive surgical technique for the treatment of idiopathic intracranial hypertension in a cadaveric model. This technique aims at establishing a communication between the intraorbital and intracranial compartments by creating a bone, dural, and periorbital window in the anterior cranial fossa. This procedure is predicated on intraorbital absorptive capability that has been demonstrated in animals and discussed in humans. Methods Three fresh cadaver heads were fixed in a head holder so as to mimic the hyperextended supine position. The procedure was conducted bilaterally in each specimen. Our technique is as follows: 1) An incision is made in the eyebrow medial to the supraorbital notch; 2) using an endoscope and a periosteal elevator, the intraorbital surface of the orbital roof is separated from the periorbita in an anteroposterior direction for a length of 1.5-2.5 cm; 3) a 1 cm of the exposed orbital roof is removed, and the dura and arachnoid are opened; and 4) slits are made in the exposed periorbita. Results We were able to create a communication between the intracranial and the intraorbital compartments in all specimens. Conclusion Our technique is new and does not require any foreign body implantation. Its applicability in humans needs to be evaluated in a clinical context.

Cerebrospinal fluid (CSF) serves numerous important functions in the central nervous system. Despite numerous reports characterizing CSF and its circulation in the subarachnoid space, our understanding of CSF outflow remains limited. Although initial work suggested that both arachnoid granulations and lymphatic capillaries shared in the role of CSF outflow, predominant work since then has focused on the arachnoid granulations. A growing body of recent evidence not only suggests the importance of both arachnoid granulations and lymphatic capillaries, but also additional contributions through transependymal passage likely share in the role of CSF outflow. Consideration of all mechanisms and pathways will help us to better understand the significance of CSF outflow, in health and disease. Here we review how the present concept of CSF outflow has evolved, including a historical review of significant findings and a discussion of the latest innovative developments.

The purpose of this paper is to describe orbitocranial penetration due to "shanking", a common mode of assault in prison facilities. We report the case of a prisoner who presented with orbital apex syndrome 5 days after an assault. He died 9 days after surgical removal of the "shank" due to a presumed ruptured traumatic aneurysm. Physicians who evaluate prisoners must maintain a high index of suspicion for penetrating injuries. The entrance site is often inconspicuous and the history may be limited in this unique population.

Susac's syndrome (SS) consists of the clinical triad of encephalopathy, branch retinal artery occlusions (BRAO) and hearing loss. It is due to a microangiopathy affecting the precapillary arterioles of the brain, retina, and inner ear (cochlea and semicircular canals). Women are more commonly affected than men (3:1); the age of onset ranges from 9 to 58 years; but young women between the ages of 20 and 40 are most vulnerable. The encephalopathy is almost always accompanied by headache which may be the presenting feature. Multifocal neurological signs and symptoms, psychiatric disturbances, cognitive changes, memory loss, and confusion may rapidly progress to dementia. The MRI shows a distinctive white matter disturbance that always affects the corpus callosum. The central callosal fibers are particularly vulnerable and central callosal holes develop as the active lesions resolve. Linear defects (spokes) and rather large round lesions (snowballs) sometime dominate the MRI findings, which include cortical, deep gray (70%) and leptomeningeal involvement (33%). Frequently, the lesions enhance and may be evident on diffusion weighted imaging (DWI). The BRAO are best evaluated with fluorescein angiography, which may show the pathognomonic multifocal fluorescence. Gass plaques are frequently present and reflect endothelial damage. Brain biopsy shows microinfarction to be the basic pathology, but more recent pathological studies have shown endothelial changes that are typical for an antiendothelial cell injury syndrome. Elevated levels of Factor VIII and von Willebrand Factor Antigen reflect the endothelial perturbation. Despite extensive evaluations, a procoagulant state has never been demonstrated. SS is an autoimmune endotheliopathy that requires treatment with immunosuppressants: steroids, cyclophosphamide, and intravenous immunoglobulin, usually in combination. Aspirin is a useful adjunct.

Background Development of retinal detachment models in small animals can be difficult and expensive. Here we create and characterize a novel, cone-rich retinal detachment (RD) model in the chick. Methodology/Principal Findings Retinal detachments were created in chicks between postnatal days 7 and 21 by subretinal injections of either saline (SA) or hyaluronic acid (HA). Injections were performed through a dilated pupil with observation via surgical microscope, using the fellow eye as a control. Immunohistochemical analyses were performed at days 1, 3, 7, 10 and 14 after retinal detachment to evaluate the cellular responses of photoreceptors, Muller glia, microglia and nonastrocytic inner retinal glia (NIRG). Cell proliferation was detected with bromodeoxyuridine (BrdU)-incorporation and by the expression of proliferating cell nuclear antigen (PCNA). Cell death was detected with terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL). As in mammalian models of RD, there is shortening of photoreceptor outer segments and mis-trafficking of photoreceptor opsins in areas of RD. Photoreceptor cell death was maximal 1 day after RD, but continued until 14 days after RD. Muller glia up-regulated glial fibriliary acidic protein (GFAP), proliferated, showed interkinetic nuclear migration, and migrated to the subretinal space in areas of detachment. Microglia became reactive; they up-regulated CD45, acquired amoeboid morphology, and migrated toward outer retina in areas of RD. Reactive NIRG cells accumulated in detached areas. Conclusions/Significance Subretinal injections of SA or HA in the chick eye successfully produced retinal detachments and cellular responses similar to those seen in standard mammalian models. Given the relatively large eye size, and considering the low cost, the chick model of RD offers advantages for high-throughput studies.

Dear Editor, We read with interest the report by Cebulla et al. [1] reporting visual hallucinations associated with Charles Bonnet syndrome (CBS) in a patient with bilateral dense vitreous hemorrhage from subarachnoid hemorrhage. The authors report rapid improvement in her cognition and cessation of the hallucinations after pars plana vitrectomy was performed in one eye. This is consistent with earlier reports where improvement of visual acuity leads to a reduction or cessation of the hallucinations in CBS [2–4]. The authors referred to the “commonly limited prognosis for hallucinations” in CBS[1]. While it is true that the hallucinations do persist in some patients, in others these hallucinations may cease spontaneously after a period of time, even if the visual loss is irreversible. In fact, it has been suggested that an acute change in visual acuity may be the trigger for the onset of visual hallucinations in CBS [5, 6] and the hallucinations cease once the visual acuity has stabilized. Patients with CBS have been treated with a variety of drugs to control the hallucinations. However, in our experience, reassurance that the hallucinations are normal, and that they are not “mad” or suffering from a psychiatric disease, are a source of great relief to patients [3]. We would also like to point out that although older age is a risk factor for CBS, this condition can occur in patients of any age group [3], even in the pediatric age group [7, 8]. Therefore, it is important to consider this diagnosis even in younger patients who present with visual hallucinations without other neurological causes.

Susac syndrome (SS) is the triad of encephalopathy, branch retinal artery occlusions (BRAOs), and hearing loss. Migraines may herald and accompany encephalopathy. Little is known about pathogenesis. Based on light microscopic findings in brain biopsy material analogous to anti-endothelial cell antibody (AECA)-mediated microvascular injury, we postulated that SS microangiopathy was attributable to AECAs. We examined serum samples from 11 patients with SS for AECAs; 9 were positive by indirect immunofluorescence and Western blot studies. A highly distinctive band on Western blots corresponding to a 50-kDa protein was observed in 8 positive SS samples; the other positive case exhibited specific reactivity with a protein band at 40 kDa. Of the 2 negative cases, 1 had been inactive since 1988; the other was an abortive variant characterized solely by BRAOs. There was enhanced surface binding of SS serum using live endothelial cell substrates compared with samples from healthy subjects. Additional serum samples from apparently healthy patients, 2 with atypical migraines, and patients with other forms of autoinflammatory disease did not show the distinctive band of immunoreactivity. SS is a distinct autoimmune endotheliopathy syndrome associated with AECAs; the antibody target seems specific in many cases and may be a disease biomarker. The exact role of AECAs in disease propagation remains unanswered.

A case of presumed embolic transient ischemic episodes and multifocal infarcts to the occipital and parietal cortices and the cerebellum of a young woman with ulcerative colitis is reported. These episodes were manifested by multifocal neurologic deficits including cortical blindness, visual hallucinations, and homonymous hemianopsia. They correlated with parenteral nutrition via a central line, presumed venous, but found to be in the subclavian artery. The complications of central venous lines are reviewed. The need for attention to neighborhood structures and unexpected symptoms, in view of the less well-recognized arterial embolic complications is emphasized.

Background The underlying etiology of pseudotumor cerebri (PTC) remains unknown, however it has been estimated that an identifiable secondary cause is present in up to 10% of PTC cases. Of these secondary associations, vitamin A is of particular interest, as vitamin A toxicity is associated with an increased intracranial pressure similar to that seen in PTC. Recently, several clinical studies have suggested that serum and CSF retinol levels may be altered in PTC. We hypothesize that increased concentrations of retinoids in the CSF might increase resistance to CSF outflow at the arachnoid granulations (AGs).

Purpose To describe the occurrence of vision-threatening orbital emphysema in patients awakening from orbital decompression surgery and to assess risk factors and preventive measures. Design Small noncomparative case series. Participants Three patients undergoing bilateral orbital two-wall decompression experienced significant orbital emphysema associated with persistent coughing and Valsalva at the time of extubation. Intervention In two patients, symptoms resolved with simple observation, whereas one patient required sedation, topical anesthesia around the endotracheal tube, and needle decompression of trapped air. Main outcome measures Visual acuity, pupils, visual fields, and sensorimotor examination. Results No patient experienced a permanent deficit of visual or sensorimotor function. Conclusions Acute orbital emphysema can occur after orbital decompression surgery despite the large bony opening created. Violent coughing spells at the time of extubation are more common in patients with a history of heavy tobacco use and may be causative. Opening the periorbita may be another specific predisposing risk factor. Knowledge of this dangerous phenomenon, along with appropriate perioperative management, may prevent this complication from occurring.

Objective Surgical approaches to the orbit require great precision and care because of the functional and aesthetic importance of this region. Conventional approaches to the posterior orbit often require bone removal, may disrupt extraocular muscles, and may create external surgical scars. We conceived a transconjunctival surgical approach to the medial intraconal space that is aided by a minimally invasive endoscopic technique and avoids muscle transection. Methods Assisted by a rigid endoscope measuring 2.7 mm in diameter, with 0- and 30-degree lenses, we made a medial conjunctival incision along the limbus to approach the medial intraconal space and optic nerve in 7 fresh cadaver heads (a total of 9 procedures). Results This approach provided direct and quick access to the medial intraconal space and intraorbital optic nerve with the use of endoscopes via an aesthetically acceptable conjunctival incision, and it provided an excellent view of the operative area. Unlike conventional techniques, this approach left the anatomy relatively undisturbed and did not require detachment of the medial rectus muscle. Conclusion The endoscopic medial transconjunctival surgical approach provides minimally invasive direct access to the medial intraconal space and the intraorbital optic nerve. The approach is easy; minimally disturbs structures; and lends itself to biopsy, drainage, and even excision of selected lesions in this region without muscle transection and with aesthetically acceptable anatomic closure.

✓In recent studies spinal surgery has replaced cardiac surgery as a leading cause of postoperative vision loss (POVL). Estimates of the incidence of POVL after spinal surgery range from 0.028 to 0.2%, but with advances in complex spinal instrumentation and the rise in annual spinal operations, POVL may see an ominous increase in its incidence. Postoperative vision loss is an uncommon but devastating complication, with unknown origin and pathogenesis. The authors undertook a literature review and summarize the current understanding of its pathophysiology, highlight the limitations of existing knowledge, and recommend practical guidelines for avoiding this devastating outcome.

We describe aggressive immunosuppressive treatment of an adolescent with Susac's syndrome (SS), a disease of the microvasculature in the brain, retina, and inner ear. Because the immunopathogenesis of SS appears to have much in common with that of juvenile dermatomyositis (JDM), the patient was treated with an approach that has been effective for severe JDM. The patient's outcome provides evidence for the importance of prompt, aggressive, and sustained immunosuppressive treatment of encephalopathic SS.

PURPOSE. To describe and validate an in vitro model of the arachnoid granulation (AG) outflow pathway for cerebrospinal fluid (CSF), by using human AG cells grown on a filter membrane support and perfused in a modified Ussing chamber at pressures analogous to normal human intracranial pressures. METHODS. Human AG cells were grown, characterized, seeded onto filter membranes, and perfused in the physiologic (basal to apical, B3A) or nonphysiologic (apical to basal, A3B) directions. Cells were fixed under pressure after perfusion and prepared for electron microscopy (EM). RESULTS. The average cellular hydraulic conductivity in the B3A direction (10 total) was 4.52 0.43 L/min per mm Hg/cm 2 with an average transcellular pressure decrease of 3.13 0.09 mm Hg. The average cellular hydraulic conductivity in the A3B direction (six total) was 0.29 0.16 L/min per mm Hg/cm 2 with an average transcellular decrease in pressure of 3.33 0.16 mm Hg. Cells perfused nonphysiologically showed a large number of dead and dying cells. EM postperfusion analysis showed that AG cells were integrally attached to the underlying filter membrane. Large extracellular cisternal spaces were visible between overlapping AG cells and vacuoles within the cytoplasm. It is possible that these spaces within and between cells represent pathways for transcellular and paracellular transport of fluid. CONCLUSIONS. The results demonstrate that AG cells in vitro show a statistically significant greater flow rate and cellular hydraulic conductivity when perfused in the physiologic versus the nonphysiologic direction under normal intracranial pressures. These results suggest that this in vitro model of the AGs can accurately replicate the unidirectional flow of CSF in vivo. (Invest Ophthalmol Vis Sci. 2006;47:3664‐3672) DOI

BackgroundThe arachnoid granulations (AGs) are projections of the arachnoid membrane into the dural venous sinuses. They function, along with the extracranial lymphatics, to circulate the cerebrospinal fluid (CSF) to the systemic venous circulation. Disruption of normal CSF dynamics may result in increased intracranial pressures causing many problems including headaches and visual loss, as in idiopathic intracranial hypertension and hydrocephalus. To study the role of AGs in CSF egress, we have grown cells from human AG tissuein vitroand have characterized their expression of those cytoskeletal and junctional proteins that may function in the regulation of CSF outflow.MethodsHuman AG tissue was obtained at autopsy, and explanted to cell culture dishes coated with fibronectin. Typically, cells migrated from the explanted tissue after 7–10 daysin vitro. Second or third passage cells were seeded onto fibronectin-coated coverslips at confluent densities and grown to confluency for 7–10 days. Arachnoidal cells were tested using immunocytochemical methods for the expression of several common cytoskeletal and junctional proteins. Second and third passage cultures were also labeled with the common endothelial markers CD-31 or VE-cadherin (CD144) and their expression was quantified using flow cytometry analysis.ResultsConfluent cultures of arachnoidal cells expressed the intermediate filament protein vimentin. Cytokeratin intermediate filaments were expressed variably in a subpopulation of cells. The cultures also expressed the junctional proteins connexin43, desmoplakin 1 and 2, E-cadherin, and zonula occludens-1. Flow cytometry analysis indicated that second and third passage cultures failed to express the endothelial cell markers CD31 or VE-cadherin in significant quantities, thereby showing that these cultures did not consist of endothelial cells from the venous sinus wall.ConclusionTo our knowledge, this is the first report of thein vitroculture of arachnoidal cells grown from human AG tissue. We demonstrated that these cellsin vitrocontinue to express some of the cytoskeletal and junctional proteins characterized previously in human AG tissue, such as proteins involved in the formation of gap junctions, desmosomes, epithelial specific adherens junctions, as well as tight junctions. These junctional proteins in particular may be important in allowing these arachnoidal cells to regulate CSF outflow.

Purpose To report the new ocular and neurologic features of West Nile virus (WNV) meningoencephalitis. Design Observational case report. Methods A 55-year-old woman presented with headache, stiff neck, visual loss, and fever 10 days after a weekend camping trip. Examination revealed vitritis, creamy yellow circular chorioretinal lesions, and peripheral visual field loss. Results Laboratory investigation indicated the patient was suffering from WNV meningoencephalitis with neuro-ocular involvement. Conclusion Ophthalmologists and infectious disease specialists should recognize that the WNV infection spectrum may include ophthalmic findings, specifically optic neuritis and multifocal chorioretinitis.

Objective To investigate the localization of somatostatin receptor types 1 and 2 in human choroid plexus (CP) and arachnoid granulations (AGs) by immunohistochemistry. Methods A prospective study was performed in an institutional setting. Immunohistochemistry was performed on 15 samples of CP and 12 samples of AGs from 15 patients who died with no signs or symptoms of intracranial disease (age range, 52-81 years). The CP samples were dissected from the lateral ventricles and AG samples were dissected from the superior sagittal sinus. Results We demonstrated the presence of both somatostatin receptor types 1 and 2 in all samples of normal human CP and AGs. Conclusions Analogous to their demonstration and to their function in kidney and ocular tissues, these receptors may be involved in the processes of cerebrospinal fluid production and absorption, and may play a role in the increased intracranial pressure of idiopathic intracranial hypertension. Clinical Relevance Somatostatin analogues have been used to treat idiopathic intracranial hypertension, a disorder of cerebrospinal fluid homeostasis. Data are scarce regarding the cell-specific distribution of somatostatin receptors in normal human CP and AGs, the sites of cerebrospinal fluid production and egress.

We report an unusual case of orbital implant migration in which the silicone plates were found to be enveloped in a pseudocapsule surprisingly infected and lined by squamous epithelium of probable conjunctival origin. An epithelial ‘plug’ found in the inferior fornix portion of the pseudocapsule might have been responsible for bacterial entry into the cavity. We discuss the literature regarding pseudocapsule formation around silicone implants and the phenomenon of capsular contracture. Both the infection and the epithelial downgrowth may have facilitated the implant migration.

The April 2007 issue of Leukemia & Lymphoma printed a Letter to the Editor by Park et al. [1] in which they reported that their patient incurred visual loss due to “possible posterior ischemic opti...

Amaurosis fugax, or fleeting loss of vision, is often attributed to embolic retinovascular disease. In this setting, there is appropriate concern for associated cerebrovascular complications. Extensive and expensive vascular evaluation may be indicated. Less often, local ocular abnormalities may mimic embolic visual loss. We describe a case of sudden, transient, monocular visual loss in a 67-year-old woman caused by Valsalva-induced intraocular bleeding from a seemingly normal iris.

PURPOSE. The brain’s arachnoid membrane with granulations is an important biological barrier whose responsibilities include the transmission of cerebrospinal fluid (CSF) and the regulation of pressure. Membrane disturbance may cause changes that are difficult to replicate with animal models, suggesting the need for a model using human arachnoid membrane with granulations for the study of conditions such as Alzheimer disease, hydrocephalus, and pseudotumor cerebri. The authors detail the development and validation of an ex vivo model of CSF outflow across human arachnoid granulations (AGs) as an approximation of in vivo conditions. METHODS. Human AGs were perfused at normal physiological pressure in physiological and nonphysiological directions for permeability data. Fluorescent particle perfusion with electron microscopy identified outflow pathways through the AGs. RESULTS. This human ex vivo model demonstrated in vivo properties of unidirectionality, particle transport, and ultrastructure, similar to our 2005 in vitro model. The average baseline hydraulic conductivity in the physiological direction (n 20) was 1.05 0.15 L/min/mm Hg/cm 2 compared with 0.11 0.03 L/min/mm Hg/cm 2 in the nonphysiological direction (n 3) under statistically equivalent (P 0.46) average normal physiological pressures (5.88 0.22 mm Hg and 6.14 0.23 mm Hg, respectively). CONCLUSIONS. The ex vivo model is feasible and herein demonstrated. These findings agree with in vivo CSF outflow. This model increases understanding of the clearance not only of CSF but also of metabolites through the arachnoid membrane. Additional evidence suggests, but does not yet prove, that CSF outflow may occur in a similar manner in the arachnoid membrane adjacent to the granulations, in addition to the flow through the AGs. This is a topic for further investigation. (Invest Ophthalmol Vis Sci. 2008;49:4721– 4728) DOI

To the Editor. —I read with interest the Case Report by Lilley et al1in the December 1990 issue of theArchives. The case of optic disc edema due to hypoxic optic neuropathy, as reported so well by the authors, adds to the limited literature on the topic and helps us understand the multiple optic disc edema mechanisms. However, the last paragraph in the report is unfortunate. It reflects the long-standing association between the poorly defined wordpapilledemaand increased intracranial pressure (ICP). (Notice that we avoid its use in patients with optic disc edema due to optic neuritis.) The authors suggest that this patient had pseudotumor cerebri (PTC) due to anemia, and, therefore, papilledema due to increased ICP. Not all cases of optic disc edema (even bilateral optic disc edema) are due to the papilledema of increased ICP. No evidence is provided in this report that ICP was

Acquired color deficiencies may correspond to a general, non-selective loss of visual sensitivity. We summarise evidence for the opposite view that, in some cases, chromatic sensitivity can be more (or less) reduced than achromatic sensitivity. This evidence is based on: (1) Disproportion between chromatic and achromatic isopters; (2) Differential damage to red-green and blue-yellow color vision; (3) Detection static perimetry; (4) The foveal photochromatic interval; (5) The two color threshold technique; (6) Spectral sensitivity on a white background; (7) Single unit and histological studies of the retina and lateral geniculate nucleus; (8) Lesions of the prestriate color area; (9) Selective damage to achromatic processes. Possible problems of interpretation are considered and a new technique for comparing chromatic and achromatic sensitivity is briefly described.

Optic disc edema with neovascularization, peripapillary hemorrhages, and exudates mimicking true papilledema occurred in three teen-aged patients with long-standing juvenile diabetes mellitus controlled by insulin. Despite the appearance of papilledema, the unusual signs, symptoms, and course of this syndrome suggest that it is an ischemic manifestation of diabetic microangiopathy within the optic papilla in the absence of adequate collateral circulation. This report confirms the existence of a diabetic optic neuropathy, and discusses its vascular pathogenesis and management.

Seventy patients with retinal strokes were seen from August 1969 to March 1972. Fifty-three of these patients had a clinical picture suggestive of retinal artery occlusion due to emboli from atheromatous disease of the carotid bifurcation. Carotid arteriograms were performed in 45 of these patients. Carotid bifurcation atheromata were demonstrated as the probable source of emboli in 43 of the 45 patients (96%). Review of a series of 100 consecutive carotid arteriograms performed in hospital patients 60 years of age or older demonstrated an overall incidence of similar carotid atheromatous disease in only 24%. The striking incidence of carotid lesions in patients with retinal stroke syndromes suggests that most retinal strokes are caused by embolization from carotid bifurcation atheromata.

Three patients with monocular visual symptoms had intraocular vascular malformations, presumably congenital, in the affected eye. Special radiographic techniques (magnification of the orbit with subtraction of overlying bone during carotid arteriography) were necessary to demonstrate the orbital perioptic vascular malformations that were responsible for the visual symptoms.

The addition of polytomography considerably increases the sensitivity of pneumoencephalography. The chiasmatic area lends itself particularly well to investigation by polytomoencephalography. In a series of 28 patients, the transverse dimension of the optic chiasm ranged from 4 to 20 mm, with a mean of 18 mm. The posterior portion of the chiasm tended to be U-shaped; its anterior portion's shape was that of a dumbbell. Intrachiasmatic tumors distort and enlarge the chiasm. The diaphragma sella is also particularly well evaluated by this technique. The study is safe, reliable, and can be repeated as needed.

• Decompression of the perioptic meninges for intractable chronic papilledema was done in a patient with a right parietal temporal glioblastoma multiforme. The patient died 39 days postoperatively. Histologic study of the optic nerves indicated fistulas in the dura compatible with cerebrospinal fluid (CSF) egress and maintenance of a normal subarachnoid space around the nerve. Two additional patients with unilateral optic nerve decompression producing bilateral resolution of papilledema were studied. We contend that egress of CSF was the principle mode of action in these three cases. How long the dural fistula remains patent is unknown. Reports in the literature show considerable variation in the effects of optic nerve decompression. Anatomic variation of the intracanalicular subarachnoid space together with differences in underlying pathologic condition, surgical technique, and patient response may explain discrepancies among the results reported. ( Arch Ophthalmol 95:97-104, 1977)

To the Editor. —In the January 1988 issue of theArchives, Dr Kushner 1 reported an interesting but atypical diplopia in a 73-year-old woman which he described as "an unusual case of acquired ocular muscle fibrosis after cataract surgery." While not anxious to deprive the medical world of the "Kushner syndrome," I am anxious to avoid this causative implication of cataract surgery and diplopia in a woman with enlarged ocular muscles and restriction of elevation that began "several weeks after surgery" and progressed "during the subsequent months." Until proved otherwise, this picture is most suggestive of euthyroid Graves' disease or "dysthyroid" orbital myopathy. Her age, signs, symptoms, laboratory results, computed tomographic scan, and clinical course were compatible with, and characteristic of, patients with this diagnosis. To suggest that such a multifocal, posterior orbital hypertrophic myopathy is due to a delayed response to the surgery or to local anesthesia is to